As is generally well known, gaskets, sheets, or mats of Electromagnetic Interference (EMI) protective materials have critical value for many systems of strategic importance for the civilian and military applications. Aerospace systems, in particular, can be compromised and even permanently disabled by EMI effects if not shielded appropriately. It is of great importance that all such materials that are integrated into fielded systems are fully capable of meeting shielding requirements.
Electronic systems and, in particular sensor systems, while critical for the operation of a multitude of weapon systems tend to be very vulnerable to Electro-Magnetic Interference (EMI), Electro-Static Discharge (ESD), and lightning. To protect these systems, shielding materials meeting stringent specifications in the areas of EMI, ESD, and lightning are regularly employed. Such materials commonly constructed from woven or non-woven fibers that are further pre-impregnated with epoxy resin to provide a broad spectrum of environmental shielding.
The pre-impregnation (prepreg) process subjects the carbon fibers to significant stresses: thermal, mechanical, etc. It is well established that at this stage, deformations and changes often occur, preventing the fibers from meeting shielding requirements. It is therefore necessary to identify such defective material before it is integrated into a system and deployed to the field.
However, direct measurement of material performance as traditionally performed and detection of defects or flaws, for example by procedure in accordance with ASTM D4935-10 standard, is not only time consuming but requires a high level of engineering expertise and involvement, resulting in significant added cost to the process and thereby to the validated material itself, particularly when testing shielding material as it being produced on a manufacturing line in a continuous roll form.
A standard radio frequency (RF) specification for such shielding materials generally covers the 2-18 gigahertz (GHz) range. a suitable system to confirm effective shielding and detect defective material must be functional throughout this range. In addition, anisotropy of electromagnetic response is a common trait among these materials, and as a result the polarization of the RF source is very significant.
Therefore, there is a need for an improved system and method for determining, in a non-destructive manner, structural and/or electromagnetic characteristics and/or properties of an electromagnetic energy (EME) shielding material during a manufacturing process thereof.